Shot distributing member for shot cleaning apparatus for gas-swept heating surfaces



Feb. 7, 1967 'r. v. HEDENTORP ET AL 3,302,699

SHOT DISTRIBUTING MEMBER FOR SHOT CLEANING APPARATUS FOR GAS-SWEPT HEATING SURFACES Filed April 19, 1965 United States Patent 3,302,699 SHUT DISTRIBUTING MEMBER FOR SHOT CLEANING APPARATUS FOR GAS-SWEPT IEATRIG SURFACES Ture Valfrid Hedentorp, Stockholm, and Oskar Julius Stigenberg, Harnas, Sweden, assignors to Aktiebolaget A. Ekstroms Maskinaifar, Stockholm, Sweden, a Swedish joint-stock company Filed Apr. 19, 1965, Ser. No. 449,257 Claims priority, application Sweden, Apr. 27, 1964, 5,223/64 4 Claims. (Ci. 165-95) The present invention relates to shot cleaning of gasswept heat exchange surfaces of heat exchangers, and is concerned, more particularly, with distributing members for shot cleaning apparatus for heat exchangers.

In US. Patent No. 2,809,018, there is disclosed a distributing member for obstructing and deflecting the fiow of cleaning particles through a pipe, extending through one of the walls of a heat exchanger comprising a casing including side walls and a top wall, one of said walls having an opening therein through which flue-gases enter the heat exchanger to flow past heat exchange surfaces disposed within said casing. The distributing member will serve to scatter the flow of cleaning particles through said pipe to make them drop all over the heat exchange surfaces to remove dust, soot and other deposits adhering thereto. The active portion'of said distributing member is usually spherically rounded, but other shapes may serve, such as conical.

Such a distributing member will cause the cleaning particles, usually steel shot, to be uniformly scattered over an area which is circular in shape. Since the heat exchangers to be cleaned have in most cases a rectangular or square cross section, there is apt to be a relative scarcity of cleaning particles at the corners of the heat exchanger, and thus the bombardment of the heat exchange surfaces will be somewhat less intense in the corners. This will be of no great importance in many cases, as there will still be a sufiicient number of cleaning particles dropping in the corners. In certain difficult cases this corner effect is, however, unwelcome. For instance, in heat exchangers connected after soda recovery-boilers for the sulphate pulp industry-the cleaning action in the corners of the square section of the heat exchanger will become insufficient, and the shot cleaning may have to be supplemented with frequent washing and rinsing of the heat exchange surfaces with alkaline solutions, which is most inconvenient. Such washing and rinsing will become necessary while the deposits in the corners of the heat exchanger tend to grow more thick than elsewhere not only because the bombardment with cleaning particles is less intense there, but also because the gas flow is, as a rule, slower in the corners than towards the center of the cross section, which will promote the growth of deposits. If, to counteract this, the cleaning is effected more frequently, or a greater quantity of cleaning particles is brought to drop against the heat exchange surfaces during each cleaning cycle, most of the heat exchange surfaces will be subjected to a tooheavy bombardment by cleaning particles so that these surfaces may suffer damage.

The problem to be solved, if an appropriate distribution of cleaning particles in heat exchangers having an angular cross section is to be achieved, will be to provide a distributing member of such a shape that it will afford a more dense distribution pattern in certain directions, such as in the direction of the diagonals for a square cross section of the heat exchanger. This may be achieved according to the invention, if the rebound sur faces of the distributing members are formed as surfaces belonging to a pyramid-like member.

3,392,699 Patented Feb. 7, 1967 In the drawing:

FIG. 1 is a side elevation of a distributing member according to the invention,

FIG. 2 is a top plan view of the distributing member in FIG. 1,

FIG. 3 is a diagrammatic top plan view of a distributing member mounted above the heat exchange surfaces of a heat exchanger having square cross section, and

FIG. 4 is a view similar to FIG. 3, but with the distributing member turned through an angle of 45 relative to FIG. 3, heating surfaces also being illustrated.

The distributing member 1 illustrated in FIGS. 1 and 2 is shaped like a regular four-sided pyramid with side faces 2. The pyramid is truncated so that a small top surface 3 is formed. The side faces 2 do not merge directly with the bottom surface 4-, but are connected thereto by rather steeply inclined surface portions 5. The provision of the surface portions 5 makes it possible to form the distributing member with a rather obtuse top, but still with a rather great height without the bottom surface becoming too large. The surface portions 5 are not active in distributing the cleaning particles, but are used for mounting the member in a box-like structure of sheet steel or the like (not illustrated). The four corner portions of the pyramid close to the bottom surface 4 may preferably be cut off, as shown, as they do not participate to any great degree in the distribution. The distributing member thus will have an eight-sided bottom surface, as shown in FIG. 2. In this manner a certain amount of material is also saved, which may be of considerable importance when the material is hard metal which may be preferable.

The size of the angle on subtended between the side faces 2 of the pyramid and the horizontal plane is determined in accordance with the extension of the heat exchange surface to be served by the distributing member in question. A suitable size of angle for a cross section area of 2 x 2 m? is about 22. If the cross section area is greater, the angle or should be increased correspondingly.

In FIG. 1 is also shown directly above the distributing member the bottom end of a pipe 6 through which the cleaning particles are fed so that they hit the distributing member.

FIGS. 3 and 4 show diagrammatically how a distributing member 1 is mounted at the center of a square representing the cross section of a heat exchanger 8. According to FIG. 3 the intersections 7 between the side faces 2 of the distributor member which is formed as a foursided pyramid are disposed in such a manner that their horizontal projections coincide with the diagonals 9 of of the heat exchanger cross section. (For the sake of clarity, the corners of the distributing member are not shown cut off as in FIGS. 1 and 2.) With the arrangement shown in FIG. 3 the corners of the heat exchanger cross section will be subjected to the action of the cleaning particles to a lesser degree than if a distributing member of the known type as set forth in the opening part of this specification is used, and this arrangement is illustrated only for comparison with that of FIG. 4 which shows the best manner of disposing the pyramid-shaped distributing member with regard to the heat exchanger cross section. The heating surfaces of the heat exchanger in FIG. 4 are denoted ill. Whereas, in FIG. 3, the edges 7 of the distributing member coincide with the diagonals 9 of square heat exchanger cross section, the distributing member has been turned through an angle of 45 in the arrangement shown in FIG. 4 so that the side faces 2 of the distributing member face the corners of the heat exchanger cross section. It may be expected that those cleaning particles hitting the side faces 2 centrally will rebound generally towards the corners of the heat exchanger cross section, and the corners, therefore, will receive at least their due share of cleaning particles. In the arrangement shown in FIG. 3, the corners will face the distributing member side edges 7, and it cannot be expected, therefore, that the corners of the cross section will receive an adequate quantity of cleaning particles.

If the heat exchanger cross section is too large for one distributing member, several such members may be arranged With suitable spacing and orientation.

In the disclosed embodiment the distributing member is basically a regular four-sided pyramid. Its shape may be modified in many respects, however, to suit it to heat eX- changer cross sections of dilferent sizes and shapes. The member need not have a regular pyramid shape, but may be irregular in difierent manners. The side faces may be more than four, or may be only three, and they may also have different relative sizes and may be differently inclined.

The cleaning particles used, mostly steel shot, will have a more or less irregular shape, which may cause different :particles to rebound in different directions, even if they should happen to hit the same spot on the distributing member.

What We claim is:

1. In heat exchanging apparatus having an angular cross-section shape and comprising gas-swept heating surfaces, the provision of pipe means for conveying cleaning shot into said apparatus and at least one stationary shot distributing member disposed below the outlet of said pipe means and above said heating surfaces, said at least one distributing member having a pyramid-like shape and being disposed with its sides facing the corners of said heat exchanging apparatus.

2. In a heat exchanger having a substantially square cross-section shape and comprising gas-swept heating surfaces, the provision of pipe means for conveying cleaning shot into said apparatus to drop over said heating surfaces, and a stationary shot deflecting member disposed beyond the outlet of said pipe means in the path of said cleaning particles, said shot deflecting member being shaped substantially as a four-sided pyramid with its sides facing the corners of said heat exchanger.

3. The arrangement as claimed in claim 2 wherein the general shape of said shot deflecting member is that of a truncated four-sided regular pyramid.

4. The arrangement as claimed in claim 2 wherein said shot deflecting member is shaped basically as a truncated regular four-sided pyramid with cutaway corner portions to render the bottom face of said member octagonalshaped.

References Cited by the Examiner UNITED STATES PATENTS 2,765,588 10/1956 Puhr Westerheide 95 X 2,946,569 7/1960 Kirkby 16595 FOREIGN PATENTS 726,744 3/1955 Great Britain.

ROBERT A. OLEARY, Primary Examiner.

T. W. STREULE, JR., Assistant Examiner. 

1. IN HEAT EXCHANGING APPARATUS HAVING AN ANGULAR CROSS-SECTION SHAPE AND COMPRISING GAS-SWEPT HEATING SURFACES, THE PROVISION OF PIPE MEANS FOR CONVEYING CLEANING SHOT INTO SAID APPARATUS AND AT LEAST ONE STATIONARY SHOT DISTRIBUTING MEMBER DISPOSED BELOW THE OUTLET OF SAID PIPE MEANS AND ABOVE SAID HEATING SURFACES, SAID AT LEAST ONE DISTRIBUTING MEMBER HAVING A PYRAMID-LIKE SHAPE AND BEING DISPOSED WITH ITS SIDES FACING THE CORNERS OF SAID HEAT EXCHANGING APPARATUS. 